A role for cytochalasin-sensitive proteins in the regulation of calcium transport in activated human lymphocytes

Abstract

Acute cytochalasin (B, A, and E) effects on 45 Ca ++ uptake in purified human lymphocytes were studied. By themselves the cytochalasins failed to alter 45 Ca ++ uptake. However, they produced a 1.5–4.0 fold augmentation of the early increase in Ca ++ transport in response to PHA, con A or periodate. Ca ++ uptake responses to Hg ++ and Zn ++ were unaffected. The enhancement of lectin stimulated 45 Ca ++ uptake was very rapid (within 2 minutes) and was seen over a broad range of lectin and cytochalasin concentrations. Taken together with the recent demonstration that cytochalasin B potentiates lectin induced mitogenesis these results suggest that actomyosinlike proteins help modulate lymphocyte responses to mitogens.